The above TKT units are a preparation course for the 5 part Teaching Knowledge Test (TKT) that will give you a score of 1-4 from the Cambridge ESOL examining body. A good score in this demonstrates familiarity with the theory of English teaching. If you wanted to do this exam you would have to arrange the examination yourself. The cost depends on the local centre. You can find a list of local Cambridge ESOL centres here.